Layer Masks - viewed
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Introduction

Let me first start by telling you that this tutorial is spread over 3 pages. Click on the blue number 2 or 3 at the top or bottom of this page to visit the other pages.

Layer Masks are a very powerful part of Photoshop and that is for a couple of reasons:

Layer Masks are editable selections that play an important role in non destructive editing

Layer Masks offer flexibility because they can be almost completely treated as a full gray scale image, which allows the use of filters, selection tools, adjustment tools, etc.

They have a visual strength, meaning that with a short look on the layers you can see how they affect the image

They offer extra flexibility by being part of vector masks, layer sets, adjustment layers, etc.

Layer masks allow you to save selections

Layer Masks are always saved when you save your document.

Layer Mask are quite often used to hide pixels, but can
also be used to mask the result of an adjustment layer.
In this introduction we're only going to focus on hiding
pixels. later on we'll see how layer masks can be used
in combination with adjustment layers and layer sets.

So how do layer masks work? A layer mask
is actually telling photoshop how to deal with the layer
it's attached to and does this by using shades of gray.
Let's focus for now only on black & white masks.

To understand layer masks you have to remember the following:

The color black in a layer mask hides the corresponding
pixels in the linked layer (actually makes those pixels
transparent).

The color white leaves the corresponding in the linked
layer intact; it doesn't do anything with them

In our example we have two layers in our layers palette;

A background layer that is green

A layer named Layer 1 that is on top and is color yellow

We also notice a black & white image on the right side
of our Layer 1; that's the
famous layer mask.

So what does that mean in our example? It means that the
black ellipse is hiding the the corresponding pixels in
the yellow layer (Layer 1).
What we see in our document
window is always the result of looking down on the layers
in the layers palette, starting at the top layer and in
most cases ending with a background layer. All these are
stacked on top of each other like playing-cards. Our yellow
'card' has
a hole in it and that's why it's the only area where we
can see the layer underneath, in our case the green layer.
The result is a yellow square with in the middle a green
ellipse.

So remember; black hides pixels (or hides the result of an adjustment layer)

This tutorial is split into several sections:

Creating a Layer Mask (all visible)

Creating a Layer Mask (all hidden)

Using a brush to paint on the Layer Mask

Active Layer Mask

Inactive Layer Mask

Unlinked Layer Mask

Disabling a Layer Mask

Deleting a Layer Mask

Editing a Layer Mask in the document window

Right click on Layer Mask (context menu)

Apply Layer Mask

Layer Mask with gray

Layer Masks and gradients

Layer Styles in combination with Layer Masks

Vector Mask

Combining a Layer Mask with a Vector Mask

Combining Layer Masks

Using clipping layers with Layer Masks

Masks and filters

Masks and adjustment layers

Masks and selections

Shortcuts

Create a Layer Mask (all visible)

You create a new mask by clicking on the Add Layer
Mask icon .
This will create by default a white mask, meaning that
no pixels of the layer will be affected; our document window
will be filled with green:

Create a Layer Mask (all hidden)

You'll create a mask that is filled with black when you
hold down the Alt key
(option key on the Mac) while clicking on the Add Layer
Mask icon .
This means that all pixels in that layer will be hidden;
our document window will be filled with white, since the
layer above is completely hidden:

Use a brush to paint on the layer mask

You
can also paint on masks using a brush. In this example I drew two lines in black.
What is black in the mask will be hidden in the layer:

Active Layer Mask

An active Layer Mask can
be recognized by:

a Layer Mask
icon in
front of the layer (marked with red circle)

a double border surrounding the
Layer Mask (marked with red arrow)

Inactive Layer Mask (layer is active instead)

An inactive Layer Mask can
be recognized by:

a brush icon in front of the layer (marked with red circle)

a double border surrounding the layer in the layers
palette (red arrow)

Unlinked Layer Mask

By default a layer and its masked are linked, meaning that
moving the layer will also move the mask or moving
the mask will also move the layer. We can unlink the
layer and its mask by clicking on the link icon .
Both layer and mask can then be moved independently. The red ellipse shows where we have removed the link.

Disable a Layer Mask

You can disable a layer mask by holding down the shift key
while clicking on the mask. The layer mask will then be marked with a large red cross.